The New Topographic Map of Mercury Marks a Milestone for Space Cartography

Mercury was the last unmapped terrestrial planet in out solar system.

by Kastalia Medrano
JHU Applied Physics Laboratory / YouTube

The United States Geologic Survey, in conjunction with a handful of other prominent research institutions, just released the first complete topographic of Mercury, and it’s beautiful. It’s also a milestone. According to Kris Becker, a USGS computer scientist and the lead investigator on the project, we already have complete topographic maps of Mars, Venus, the moon, and of course the Earth, plus smaller celestial bodies (asteroids, comets) in our solar system and some in-progress regional mapping of Pluto, which is a “dwarf planet” on our jerseys, but the ninth planet in our hearts. Mercury was the final non-gaseous planet in our solar system without such a map.

Done and done.

The map is courtesy of the first spacecraft ever to orbit Mercury, NASA’s MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER). MESSENGER launched in 2004, and since beginning this mission in March 2011 the spacecraft has orbited the Red Planet 4,104 times, which is why this new map is as detailed as it is — it stitches together more than 100,000 images to form the final, complete picture. MESSENGER has been doing such a good job that NASA keeps pushing back its retirement date; it finished its original work in 2012, and its mission has since been extended twice. To date, MESSENGER has traveled 4.9 billion miles.

Mercury’s proximity to the sun presented some challenges, as certain images came back in shadow and some came back overexposed, so to speak, in accordance with MESSENGER’s position in relation to the planet’s orbit. The finished map cleanly details Mercury’s highest and lowest elevations, including the Rachmaninoff basin, where scientists believe the planet’s most recent volcanic deposits lie.

“Production of the digital elevation model of Mercury is the capstone of a significant scientific achievement of the MESSENGER mission,” said Ralph McNutt, MESSENGER team member and Johns Hopkins University Applied Physics Laboratory scientist, in the USGS press release. “This product reveals the entirety of the innermost planet of the solar system, less than half glimpsed during the three flybys of Mercury carried out by the Mariner 10 spacecraft over 40 years ago. As such, it is yet another indicator of the turning point from reconnaissance through exploration of Mercury by MESSENGER to an era of intensive study of Mercury in years to come.”

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